Bose Soundtouch not working

My problem is that Bose soundtouch does not work on different radios and ssids. Even though they are on the same subnet. I´ve alot of settings and setups but nothing seems to be working. Until yesterday I tried ASUS Original firmware then it worked. But I do NOT want to use that horrible webGUI
The Device is streaming fine but when you want to control radio station/stream spotify it can´t be contacted via Bose soundtouch app if its not on exatly the same SSID.

Any ideas? Actually I have similar issues at an customer that we sold Pakedge Accesspoints to. Theyre expensive and great performing products. But some sort of service does not forwards between SSID/Radios on Soundtouch devices.

Shot in the dark, but could it be because the Bose soundtouch uses the default class C subnet of 192.168.1.1 as does your Router?

Can you change your Bose to use a static IP address that is not being used for your LAN to test? If you are using Bluetooth try setting Bluetooth co-existence in your Advanced Wireless settings for interference mitigation.